Advanced commissioning
7.7 Safe Torque Off (STO) safety function
SIMATIC ET 200pro FC-2 converter
Operating Instructions, 04/2018, FW V4.7 SP10, A5E34257324B AF
119
Application examples for the STO function
The STO function is suitable for applications where the motor is already stationary, or can
come to a standstill in a short time through friction without posing any danger. STO does not
shorten the run-on of machine components with high inertia.
Examples
Possible solution
When the Emergency Stop button is pressed, it is
not permissible that a stationary motor starts unin-
tentionally.
•
Wire the Emergency Stop button to a fail-
safe input of the ET 200pro system.
•
Select the STO function via the fail-safe
input and the interface module of the
ET 200pro in the converter.
A central Emergency Stop button ensures that
several drives cannot start unintentionally.
•
Evaluate the Emergency Stop button in a
central control.
•
Select STO via PROFIsafe.
7.7.2
((Precondition for using STO))
Prerequisite for STO use
In order to use the STO safety function, the machine manufacturer should have already
performed a risk assessment, e.g. in compliance with EN ISO 1050, "Safety of machinery -
Principles of risk assessment". The risk assessment must confirm that the inverter is
permitted for use in accordance with SIL 2 or PL d.
7.7.3
Commissioning STO
7.7.3.1
Commissioning tool
We strongly recommend that you commission the safety functions using the STARTER PC
tool.
If you use STARTER for commissioning, then you set the functions using the graphic screen
forms and you do not have to work with parameters. In this case, you can ignore the
parameter tables in the following sections.
Table 7- 14 STARTER commissioning tool (PC software)
Download
Order number
STARTER
http://support.automation.siemens.com/WW/v
6SL3255-0AA00-2CA0
PC Connection Kit, includes STARTER DVD and
USB cable